CN116666591A - Silicon-based material and electrochemical device comprising same - Google Patents

Silicon-based material and electrochemical device comprising same Download PDF

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Publication number
CN116666591A
CN116666591A CN202310725979.8A CN202310725979A CN116666591A CN 116666591 A CN116666591 A CN 116666591A CN 202310725979 A CN202310725979 A CN 202310725979A CN 116666591 A CN116666591 A CN 116666591A
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silicon
based material
carbon
particle size
particles
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刘瑞芳
赵俊
杨波
周湘江
贺劲鑫
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Lanxi Zhide New Energy Materials Co ltd
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Lanxi Zhide New Energy Materials Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Engineering & Computer Science (AREA)
  • Electrochemistry (AREA)
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  • General Chemical & Material Sciences (AREA)
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  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The application provides a silicon-based material and an electrochemical device containing the silicon-based material, and particularly relates to the technical field of battery materials. The particle size of the silicon-based material satisfies (D V,90 ‑D V,10 )/D V,50 1.0 to 3.0, wherein D V,50 5.0-20.0 mu m; the silicon-based material comprises silicon-based composite particles, wherein the silicon-based composite particles comprise a porous matrix and silicon nano particles distributed in pore channels of the porous matrix. By optimizing and collocating the particle size distribution of the silicon-based material, the processing performance of the silicon-based material is improved, and the electrochemical package containing the silicon-based materialThe device has better circulation stability.

Description

Silicon-based material and electrochemical device comprising same
Technical Field
The application relates to the technical field of battery materials, in particular to a silicon-based material and an electrochemical device containing the silicon-based material.
Background
Silicon has extremely high theoretical specific capacity and can form Li under normal temperature condition 15 Si 4 The alloy has theoretical capacity reaching 3579mAh/g, and is being used for replacing the traditional graphite cathode to become a new generation of cathode material of the high specific energy secondary battery. However, the silicon-based negative electrode has the problem of large volume expansion in the lithium intercalation process, the volume expansion can reach 300% under the condition of full lithium intercalation, and repeated volume expansion and contraction in the charge and discharge processes easily cause repeated damage and regeneration of an SEI film on the surface of the electrode, and the capacity of the battery is attenuated; further, the particles of the negative electrode material will be pulverized and lose efficacy from electrical contact, both of which lead to a reduction in battery life, limiting its industrial application. In recent years, the volume expansion of the silicon-based anode material has been reduced to some extent by optimizing the structure and interface thereof, but such improvement is not sufficient for practical use of the silicon anode.
Disclosure of Invention
Aiming at the problems in the prior art, a silicon-based material is provided, silicon nano particles are uniformly deposited in the pore canal of a porous matrix, the lithium intercalation expansion of the silicon nano particles is limited, and the particle size distribution of the silicon-based material is optimized and matched on the basis, so that the cycle performance and the processing performance of the silicon-based material are improved.
According to one aspect of the present application, there is provided a silicon-based material having a particle size satisfying (D V,90 -D V,10 )/D V,50 0.9 to 3.0, wherein D V,50 5.0-20.0 mu m;
the silicon-based material comprises silicon-based composite particles, wherein the silicon-based composite particles comprise a porous matrix and silicon nano particles distributed in pore channels of the porous matrix.
Optionally, the silicon nanoparticles have a size of 0.4 to 10nm and/or the silicon-based material has a content of 10 to 90wt.% of elemental silicon.
Optionally, a pole piece made of the silicon-based materialThe compaction density of the pole piece is 1.5 cm to 1.7cm 3 At/g, the percentage of broken particles is less than 30%.
Preferably, the broken particles comprise less than 10%.
Optionally, the silicon-based material has a powder compaction density of 0.8-2.0 g/cm at a pressure of 1 ton 3 。
Optionally, the particle size distribution of the silicon-based material satisfies at least one of the following conditions:
(1)D V,min 0.3-3.0 mu m;
(2)D V,10 1.0-8.0 mu m;
(3)D V,max 20.0-50.0 μm.
Optionally, the particle size distribution curve of the silicon-based material has only one maximum point A 1 The A is 1 The grain diameter is 5.0-20.0 mu m.
Optionally, the particle size distribution differential curve of the silicon-based material is at the maximum point A 1 Has a minimum point a 1 The a 1 The grain diameter of the particles is 0.8-5.0 mu m.
Optionally, the particle size distribution curve of the silicon-based material has at least two maxima points B 1 And B 2 The B is 1 The particle diameter of the part is 0.3-5.0 mu m, and the part B is 2 The grain diameter is 5.0-20.0 mu m.
Optionally, the specific surface area of the silicon-based material is 0.1-50 m 2 Per gram, the total pore volume is 0.001-0.05 cm 3 /g。
Optionally, the porous matrix comprises one or more of a porous carbon skeleton, a porous metal oxide skeleton, a porous metal organic skeleton, and a porous organic-inorganic hybrid material skeleton.
Optionally, the silicon nanoparticles are based on elemental silicon, and optionally comprise at least one of a silicon oxygen compound, a silicon carbon compound, a silicon nitrogen compound, a silicon phosphorus compound, and the like.
Optionally, the silicon-based material further comprises a carbon material.
Preferably, the carbon material comprises at least one of graphite, graphene, carbon nanotubes, carbon fibers, carbon nanofibers, carbon nanoparticles, and carbon nanocarbon;
further preferably, the carbon material is present in the silicon-based material in a ratio of 0 to 90wt.%;
further preferably, the carbon material has a dimension in at least one direction of 0.5 to 20 μm.
In a second aspect of the present application, there is provided a negative electrode comprising a negative electrode active material comprising a silicon-based material as described above.
In yet another aspect of the present application, there is provided an electrochemical device comprising a negative electrode comprising the silicon-based material of the first aspect.
Compared with the prior art, the application has at least the following beneficial effects:
according to the silicon-based material provided by the application, the silicon nano particles are dispersed in the pore canal of the porous matrix, and compared with larger silicon particles, the silicon nano particles have smaller volume expansion during lithium intercalation, and the pore canal network of the porous matrix can limit the expansion of silicon intercalation, so that the structural stability of the silicon-based material in the charge and discharge processes is improved.
According to the silicon-based material provided by the application, the particle size distribution of the silicon-based material is optimized, and the small-particle-size particles and the large-particle-size particles are matched, so that the compaction density of the silicon-based material is improved; the granularity distribution of the silicon-based material is further regulated and controlled and optimized by introducing carbon material particles into the silicon-based material; meanwhile, the grading ensures that the stress caused by the volume expansion of the silicon-based material realizes migration and dispersion in a silicon-based material grading system, the expansion rate of the electrode is reduced, and the cycling stability is improved.
The cathode on the electrochemical device provided by the application has higher compaction density; in addition, the strength of the silicon-based material after reasonable grading is improved, the silicon-based composite material has higher crushing resistance, the silicon-based composite material is prevented from being crushed in the rolling process, the particles are pulverized and lose electrical contact, the secondary battery is ensured to have higher capacity, and the processing performance of the silicon-based material is improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a particle size distribution curve of a silicon-based material provided in example 1;
FIG. 2 is a particle size distribution curve of a silicon-based material provided in example 2;
FIG. 3 is a graph showing the compaction density of 1.7g/cm for a silicon-based material provided in example 2 3 SEM picture of the time slice;
FIG. 4 is a particle size distribution curve of a silicon-based material provided in example 3;
FIG. 5 is a graph of the compacted density of 1.6g/cm for the silicon-based material provided in comparative example 2 3 SEM pictures of the pole pieces at time;
fig. 6 is a full cell cycle stability picture of the silicon-based materials provided in examples 1 to 5 and comparative examples 1 and 2.
Detailed Description
Embodiments of the present application will be described in detail below with reference to embodiments and examples, but it will be understood by those skilled in the art that the following embodiments and examples are only for illustrating the present application and should not be construed as limiting the scope of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
As analyzed in the background of the application, the large volume expansion of silicon materials is the biggest problem limiting the industrial application of silicon-based cathodes. In order to solve the problem, chemical vapor deposition of a silicon-containing precursor on a porous matrix is proposed, so that silicon nanoparticles are dispersed and filled in a pore structure of the porous matrix to form a silicon-based composite material, and the structure can effectively relieve the volume expansion of silicon in the charge and discharge process. However, the inventors found that when the silicon-based composite particles are used as a negative electrode, the particles are easily crushed in the case of an unsuitable particle size distribution, and the particles are pulverized to lose electrical contact, and the battery cycle performance is deteriorated, so that the excellent performance of the silicon-based composite material cannot be fully exerted.
In order to further improve the performance of the silicon-based composite material, the particle size distribution of the silicon-based composite material particles is optimized and matched. According to a first aspect of the present application, there is provided a silicon-based material having a particle size satisfying (D V,90 -D V,10 )/D V,50 0.9 to 3.0, wherein D V,50 5.0-20.0 mu m; the silicon-based material comprises silicon-based composite particles, wherein the silicon-based composite particles comprise a porous matrix and silicon nano particles distributed in pore channels of the porous matrix.
(D V,90 -D V,10 )/D V,50 The concentration of the material particle size can be characterized as the gauge of the material. Wherein D is V,10 、D V,50 、D V,90 The particle diameters are respectively corresponding to the cumulative volume fractions of 10%, 50% and 90% in the volume-based distribution. The concentration of the silicon-based material particles is 0.9-3.0. In the diameter range, larger particles and smaller particles in the silicon-based material can realize better grading, particles with different particle sizes are mixed, and especially particles with smaller particle sizes can be filled in gaps among the larger particles, so that the composite material is beneficial to obtaining higher compaction density and mechanical strength, and the cycling stability of the battery is beneficial to being improved when the composite material is used as a negative electrode material. If the diameter distance is too small, the requirement on classification equipment is high, the number of particles with qualified size is reduced, the processing cost is high, and the difficulty is high; on the other hand, too concentrated particle size may result in voids between the particles of the material, which are prone to damage during the roll preparation process. If the diameter distance is too large, the particle size distribution of the silicon-based material is too wide, the oversized particles are easy to pierce the pole piece in the pole piece manufacturing process, the processing performance is poor, and part of the particles can be crushed and pulverized in the rolling process; or the qualified pole piece density is difficult to reach, and the improvement of the volume energy density is limited. In some embodiments of the present application, the silicon-based composite material preferably has a gauge of, but not limited to, 0.9 to 1.3, 1.1 to 1.5, 13 to 1.6, 1.5 to 1.8, 1.6 to 2.0, etc.
The silicon-based material comprises silicon-based composite particles, wherein the silicon-based composite particles comprise a porous matrix and silicon nano particles distributed in pore channels of the porous matrix. The silicon nano particles are formed in situ in the pore canal of the porous matrix through chemical vapor deposition, have smaller size and smaller than 10nm, reduce stress concentration caused by the expansion of silicon intercalation lithium, and avoid the breakage of the silicon particles; the silicon nano particles are distributed in the porous matrix in a dispersing way, the porous matrix is used as a buffer matrix, the volume expansion of the silicon particles in the charging and discharging process is effectively buffered on the porous matrix, the expansion rate of the composite electrode is reduced, and the cycling stability is improved. In some embodiments, the silicon nanoparticles have a size of 0.4 to 10nm. In some embodiments, the silicon nanoparticles preferably have a size of 0.4 to 5nm, more preferably 0.4 to 2nm.
In some embodiments, the silicon-based material has a content of elemental silicon of 10 to 90wt.%. The silicon element content in the silicon-based material is typically, but not limited to, 10-20 wt.%, 15-40 wt.%, 30-60 wt.%, 40-70 wt.%, 50-80 wt.%, 60-90 wt.%, etc.
The properly graded silicon-based material has a higher compacted density with less broken particles in a degree of roll-in process. In some embodiments, the silicon-based material has a powder compaction density of 0.8 to 2.0g/cm at a pressure of 1 ton 3 . In some embodiments, the pole piece made of the silicon-based material has a compacted density of 1.5-1.7 cm 3 At/g, the percentage of broken particles is less than 30%. Preferably, the broken particles comprise less than 10%.
D V,min Refers to the particle size of the smallest particles in the material; d (D) V,max Refers to the particle size of the largest particles in the material; d (D) v,10 Refers to the particle size corresponding to the cumulative volume fraction of 10% in the volume-based distribution. In some embodiments, the particle size distribution of the silicon-based material satisfies at least one of the following conditions: (1) D (D) V,min 0.3-3.0 mu m; (2) D (D) V,10 1.0-8.0 mu m; (3) D (D) V,max 20.0-50.0 μm.
In some embodiments, the particle size distribution curve of the silicon-based material has only one maxima point A 1 The A is 1 5.0-20.0 μm. In the particle size distribution of the silicon-based material, the particle size is A 1 The particles of (2) occupy the highest volume content. In some embodiments, a 1 Typical but not limited to 5.0 to 8.0 μm, 6.0 to 9.0 μm, 8.0 to 12.0 μm, 10.0 to 15.0 μm, etc.
And differentiating the particle size distribution curve to obtain a particle size distribution differential curve. In some embodiments, the differential particle size distribution curve of the silicon-based material is at the maximum point A of the particle size distribution curve 1 Has a minimum point a 1 The a 1 The grain diameter of the particles is 0.8-5.0 mu m. Compared with the common single maximum particle size distribution curve, A in the differential curve 1 Point a of previous minimum value 1 The presence of (a) means A 1 The prior art is distributed with more small-granularity particles, and the two stages of the particles are matched with each other to effectively improve the compaction density of the pole piece. In some embodiments, a 1 The particle size is typically, but not limited to, 0.8 to 1.2. Mu.m, 1.0 to 1.5. Mu.m, 1.3 to 1.8. Mu.m, 1.5 to 2.0. Mu.m, 1.8 to 2.5. Mu.m, 2.2 to 3.0. Mu.m, etc.
In some embodiments, the particle size distribution curve of the silicon-based material has at least two maxima points B 1 And B 2 The B is 1 The particle diameter of the part is 0.3-3.0 mu m, and the part B is 2 The grain diameter is 5.0-20.0 mu m. In some embodiments of the application, B 1 The particle size is typically, but not limited to, 0.3 to 1.0 μm, 1.0 to 1.5 μm, 1.5 to 2.0 μm or 2.0 to 3.0 μm. In some embodiments, B 2 The particle size is typically, but not limited to, 5.0 to 8.0 μm, 8.0 to 10.0 μm, 10.0 to 15.0 μm or 15.0 to 20.0 μm. The particle size distribution curve with two maximum points, namely a double-peak particle size distribution curve, is usually a mixture of two particle size distribution ranges, and the two grading can better utilize pores among large-particle-size particles, so that the compaction density of the cathode material is improved.
In some embodiments, the specific surface area of the silicon-based material particles is 0.1 to 50m 2 Per gram, the total pore volume is 0.001-0.05 cm 3 /g, preferably of siliconThe specific surface area of the base material particles is 0.5-10 m 2 Per gram, the total pore volume is 0.001-0.035 cm 3 /g。
In some embodiments, the porous matrix comprises one or more of a porous carbon skeleton, a porous metal oxide skeleton, a porous metal organic skeleton, and a porous organic-inorganic hybrid material skeleton; the silicon nanoparticles comprise at least one of elemental silicon, a silicon oxygen compound, and a silicon alloy. In some embodiments, the silicon nanoparticles are based on elemental silicon, optionally comprising at least one of a silicon oxygen compound, a silicon carbon compound, a silicon nitrogen compound, a silicon phosphorus compound, and the like.
In some embodiments, the silicon-based material further comprises a carbon material; preferably, in some embodiments, the carbon material comprises at least one of graphite, graphene, carbon nanotubes, carbon fibers, carbon nanofibers, carbon nanoparticles, and carbon nanocarbon; further preferably, in some embodiments, the carbon material is present in the negative electrode material at a ratio of 0 to 90wt.%; further preferably, in some embodiments, the carbon material has a dimension in at least one direction of 0.5 to 20 μm. The addition of the carbon material is beneficial to forming proper grading with the silicon-based material, improving the compaction density of the material, relieving the lithium intercalation expansion of the silicon-based material particles, reducing the expansion rate of the pole piece and improving the circulation stability. However, the specific capacity of the resulting composite material is reduced by a corresponding reduction in the silicon content upon addition of the carbon material, and the carbon material ratio is therefore not preferred to be too large. In some embodiments, the carbon material is typically, but not limited to, 0 to 5wt.%, 5 to 10wt.%, 10 to 20wt.%, 20 to 30wt.%, 30 to 50wt.% of the silicon-based material.
According to a second aspect of the present application, there is provided an anode comprising an anode active material comprising a silicon-based material as described above.
According to still another aspect of the present application, there is provided an electrochemical device comprising a negative electrode comprising the silicon-based material of any one of the above.
The application is further illustrated by the following specific examples and comparative examples, however, it should be understood that these examples are for the purpose of illustration only in greater detail and should not be construed as limiting the application in any way. The raw materials used in the examples and comparative examples of the present application were conducted under conventional conditions or conditions recommended by the manufacturer, without specifying the specific conditions. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Preparation of (one) silicon carbon composite material
A silicon-based composite material is provided, and the specific preparation process is as follows:
1. walnut shell is added in N 2 Heating to 800 ℃ at 2 ℃/min in the atmosphere and maintaining for 2 hours at 20% CO 2 -N 2 Heating the mixture (based on volume concentration) to 900 ℃ and maintaining for 2 hours, and crushing and grading the obtained material to obtain the porous carbon.
2. Placing porous carbon in an atmosphere furnace, and adding N 2 Heating from room temperature to 600 ℃ at 2 ℃/min in the atmosphere; at 20% SiH 4 -N 2 Maintaining the mixture in a mixed atmosphere (based on volume concentration) at 600 ℃ for 30 hours; and at N 2 Naturally cooling under protection to obtain the silicon-based composite material. Wherein the content of silicon element is 45%.
Preparation of (II) silicon-based materials
For the purpose of the present application, the silicon-based material may be crushed to a certain particle size by means of a jet mill, ball milling, etc., and the crushed particle size may be controlled by adjusting parameters such as the size and rotation speed of inlet and outlet damper of the jet mill, etc., or by sieving after ball milling, etc., as known in the art.
Example 1
Adding the silicon-based composite material into a jet mill for crushing and grading to obtain the silicon-based composite material with the granularity of 0.4-30 mu m and the (D) V,90 -D V,10 )/D V,50 1.78, FIG. 1 shows a particle size distribution curve, which shows a unimodal distribution, with a maximum point A 1 The particle size was 9.14. Mu.m. The detailed particle size distribution data are shown in Table 1.
Table 1 particle size distribution table (in μm) for silicon-based materials of examples
Examples D V,min D V,10 D V,50 D V,90 D V,max (D V,90 -D V,10 )/D V,50
Example 1 0.4 2.4 7.3 15.5 30.0 1.78
Example 2 0.4 1.8 7.0 15.2 27.9 1.91
Example 3 0.4 2.9 13.4 19.5 39.7 1.25
Example 4 2.3 5.2 8.9 18.5 19.9 1.49
Example 5 2.3 7.2 15.9 21.5 22.1 0.90
Example 6 0.6 1.3 7.5 23.8 25.2 3.00
Comparative example 1 0.5 0.8 13.4 45.2 48.3 3.30
Comparative example 2 2.3 8.1 16.2 21.2 22.5 0.81
Example 2
Adding the silicon-based composite material into a jet mill for crushing and grading to obtain particles with the particle sizes of 0.4-2 mu m and 2-30 mu m respectively, taking 90wt.% of the particles with the particle sizes of 2-30 mu m, mixing with the particles with the particle sizes of 0.4-2 mu m, and performing ball milling to form (D) V,90 -D V,10 )/D V,50 1.91 silicon-based material. FIG. 2 shows the particle size distribution curve and the differentiation thereof, and the detailed particle size distribution data are shown in Table 1.
The particle size distribution curve of the silicon-based material only has one maximum point A 1 9.18 μm; the particle size distribution differential curve is A 1 Has a minimum point a 1 At a diameter of 1.76 μm, it can be seen that the silicon-based material has slightly more particles in the range of 0.38 to 2 μm than in example 1. More fine particles can further increase the diameter distance of the anode material, thereby increasing the compaction density and the electrochemical performance of the material.
FIG. 3 is a graph showing a pole piece made of the silicon-based material of example 2 when the compacted density of the pole piece reaches 1.7g/cm 3 SEM pictures in this case show that the proportion of broken particles is less than 10%.
Example 3
Adding the silicon-based composite material into a jet mill for crushing and grading to obtain particles with the particle sizes of 0.4-6.5 mu m and 6.5-40 mu m respectively, taking 70wt.% of the particles with the particle sizes of 6.5-40 mu m, mixing with the particles with the particle sizes of 0.4-6.5 mu m, and performing ball milling to form (D) V,90 -D V,10 )/D V,50 1.25 of a negative electrode material.FIG. 4 is a graph of the particle size distribution, which shows a bimodal appearance with two maxima at corresponding particle sizes of 3.26 μm and 14.25. Mu.m. The detailed particle size distribution data are shown in Table 1.
Example 4
A silicon-based material was prepared according to the same method as in example 1, except that: (D) of the classified silicon-based material particles V,90 -D V,10 )/D V,50 1.49, D V,50 8.9 μm, D V,10 5.2 μm. The detailed particle size distribution data are shown in Table 1.
Example 5
A silicon-based material was prepared according to the same method as in example 1, except that: the obtained silicon-based composite material particles D V,50 Graphite particles with the mass ratio of 15 μm are mixed according to 10:1 to prepare the cathode material. The detailed particle size distribution data are shown in Table 1.
Example 6
A silicon-based material was prepared according to the same method as in example 1, except that: (D) of the classified silicon-based material particles V,90 -D V,10 )/D V,50 Is 3.00D V,50 7.5 μm, D V,10 1.3 μm. The detailed particle size distribution data are shown in Table 1.
Comparative example 1
The difference from example 1 is that the silicon-based composite material was crushed by adding it to a jet mill to obtain D V,50 13.4 μm, D V,10 Is 0.8 μm, D V,90 45.2 μm, (D) V,90 -D V,10 )/D V,50 And 3.3, obtaining the cathode material.
Comparative example 2
The difference from example 1 is that the silicon-based composite material was crushed by adding it to a jet mill to obtain a silicon-based material D V,50 16.2 μm, D V,10 8.1 μm, D V,90 21.2 μm, (D) V,90 -D V,10 )/D V,50 0.81.
FIG. 5 is a sheet of silicon-based material of comparative example 2 with a compacted density of 1.6g/cm 3 SEM pictures at this time, it can be seen that greater than 50% of the particlesThe granules are crushed. The cathode prepared from the silicon-based material is extremely easy to be in particle pulverization failure due to expansion of silicon intercalation lithium in the cycle process of a lithium ion battery, and the cycle life is reduced.
Test example 1
The particle size distribution of the silicon-based materials of examples 1 to 6 and comparative examples 1 and 2 was measured with a laser particle size distribution meter. Fig. 1, 2 and 4 show particle size distribution curves of examples 1, 2 and 3.
Test example 2
The silicon-based materials of examples 1 to 6 and comparative examples 1 and 2 were subjected to powder compaction density measurement and held at a pressure of 1t for 10 seconds to obtain compaction density test data, and the results are shown in table 2.
Manufacturing a pole piece: uniformly stirring and mixing the silicon-based material, the binder polyacrylic acid and the solvent deionized water according to the mass ratio of 95:4:120, uniformly coating the mixture on a negative electrode current collector, rolling the mixture on a roll squeezer to a specific compaction density, and drying the mixture at 100 ℃ to obtain the negative electrode plate.
Test example 3
The silicon-based materials of examples 1 to 6 and comparative examples 1 and 2 were respectively prepared into negative electrode tabs, and soft-pack batteries were prepared and tested for electrical properties using a conventional method. The soft package battery is prepared in a dehumidification room with the dew point of-45 ℃. The battery is subjected to charge-discharge cyclic test by a blue-blog (LANBTS) battery test system, and the specific test method comprises the following steps:
(1) Manufacturing a positive plate: liCoO as positive electrode active material 2 Uniformly stirring and mixing the conductive agent SuperP, the binder PVDF and the solvent NMP according to the mass ratio of 92:3:5:150, uniformly coating the mixture on the positive electrode current collector, and drying the mixture at 80 ℃ to obtain the positive electrode plate.
(2) Manufacturing a negative plate: and uniformly stirring and mixing a negative electrode active material (active material composition is 20wt.% of silicon-based material and 80wt.% of graphite negative electrode material), a conductive agent SuperP, a binder polyacrylic acid and solvent deionized water according to a mass ratio of 95:1:4:120, uniformly coating the mixture on a negative electrode current collector, and drying at 100 ℃ to obtain the negative electrode plate.
(3) The positive plate and the negative plate are separated by square lamination and polypropylene isolating filmAnd (3) manufacturing a battery core, packaging the battery core into an aluminum-plastic bag, injecting electrolyte with corresponding capacity into the aluminum-plastic bag, and vacuum sealing to obtain the soft-package battery. The electrolyte is LiPF 6 EC and DEC mixtures of (c), wherein LiPF 6 The concentration is 1mol/L, and the volume ratio of EC to DEC is 1:1.
(4) The chemical composition comprises the following components: forming a battery after filling and sealing, standing in a constant temperature box at 25 ℃ for 12 hours, then charging to 3.3V at a constant current of 0.02C, standing for 30min, charging to 3.8V at a constant current of 0.025C, standing for 10min, and charging to 4.2V at a constant current of 0.33C; and vacuumizing and shearing the air bag of the formed battery, then carrying out capacity division, charging to 4.45V at a constant current of 0.33C, standing for 10min, discharging to 3V at a constant current of 1C, standing for 10min, discharging to 3V at a constant current of 0.33C, and ending the capacity division. The ratio of the discharge capacity divided by the charge capacity in the formation of the soft pack battery into the capacity is the first efficiency of the battery.
(5) Volumetric energy density testing: taking the partitioned battery cell, wherein the capacity of the capacitor discharge is D, the unit is mAh, measuring the length, width and thickness of the battery cell at the moment, and calculating to obtain the volume V of the battery cell, and the unit is mm 3 Volumetric energy density calculation: (DX3.89×1000)/V in Wh/L.
(6) And (3) 25 ℃ cycle test: placing the battery in a constant temperature box at 25 ℃, charging to 4.45V at a constant current of 1C, and charging to 0.1C at a constant voltage of 4.45V; and after standing for 10min, discharging the 1C constant current to 3.0V, standing for 10min, repeating the charging and discharging steps until the discharge capacity is lower than 80% of the first-cycle discharge capacity, and stopping until the cycle number is the cycle life of the soft-package battery.
(7) And (3) pole piece expansion rate test: the battery after 25 ℃ cyclic test was disassembled in a glove box, the pole piece was cleaned with DEC and the thickness of the pole piece was measured. The expansion rate is calculated by the following steps: (full electrode state pole piece thickness-fresh pole piece thickness)/fresh pole piece thickness x 100%.
The data obtained are presented in Table 2.
TABLE 2
As can be seen from table 2, by optimizing the particle size distribution of the anode material particles, the compacted density of the anode materials of examples 1 to 6 was significantly improved compared to comparative examples 1 and 2, which had a higher volumetric energy density, and at the same time, the effective buffering and dispersion of stress, the expansion rate of the pole piece was lower, so that the cycle stability of the composite material was improved, and the cycle life was significantly longer than comparative examples 1 and 2.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application.

Claims (13)

1. A silicon-based material characterized in that the particle size of the silicon-based material satisfies (D V,90 -D V,10 )/D V,50 0.9 to 3.0, wherein D V,50 5.0-20.0 mu m;
the silicon-based material comprises silicon-based composite particles, wherein the silicon-based composite particles comprise a porous matrix and silicon nano particles distributed in pore channels of the porous matrix.
2. The silicon-based material according to claim 1, wherein the silicon nanoparticles have a size of 0.4-10 nm; and/or the silicon element content in the silicon-based material is 10-90 wt.%.
3. The silicon-based material according to claim 1, wherein the compacted density of the pole piece made of the silicon-based material is 1.5-1.7 cm 3 At/g, the percentage of broken particles is less than 30%;
preferably, the broken particles comprise less than 10%.
4. The silicon-based material according to claim 1, wherein the powder compaction density of the silicon-based material at a pressure of 1 ton is 0.8-2.0 g/cm 3 。
5. The silicon-based material of claim 1, wherein the particle size distribution of the silicon-based material meets at least one of the following conditions:
(1)D V,min 0.3-3.0 mu m;
(2)D V,10 1.0-8.0 mu m;
(3)D V,max 20.0-50.0 μm.
6. The silicon-based material according to claim 5, wherein the particle size distribution curve of the silicon-based material has only one maximum point a 1 The A is 1 The grain diameter is 5.0-20.0 mu m.
7. The silicon-based material according to claim 6, wherein the particle size distribution differential curve of the silicon-based material is at the maximum point a 1 Has a minimum point a 1 The a 1 The grain diameter of the particles is 0.8-5.0 mu m.
8. The silicon-based material according to claim 5, wherein the particle size distribution curve of the silicon-based material has at least two maxima B 1 And B 2 The B is 1 The particle diameter of the part is 0.3-5.0 mu m, and the part B is 2 The grain diameter is 5.0-20.0 mu m.
9. The silicon-based material according to any one of claims 1 to 8, wherein the specific surface area of the silicon-based material is 0.1 to 50m 2 Per gram, the total pore volume is 0.001-0.05 cm 3 /g。
10. The silicon-based material according to any one of claims 1 to 8, wherein the porous matrix comprises one or more of a porous carbon skeleton, a porous metal oxide skeleton, a porous metal organic skeleton, and a porous organic-inorganic hybrid material skeleton; and/or the number of the groups of groups,
the silicon nano particles are mainly composed of elemental silicon, and optionally comprise at least one of silicon oxygen compounds, silicon carbon compounds, silicon nitrogen compounds and silicon phosphorus compounds.
11. The silicon-based material according to any one of claims 1 to 8, further comprising a carbon material;
preferably, the carbon material comprises at least one of graphite, graphene, carbon nanotubes, carbon fibers, carbon nanofibers, carbon nanoparticles, and carbon nanocarbon;
further preferably, the carbon material is present in the silicon-based material in a ratio of 0 to 90wt.%;
further preferably, the carbon material has a dimension in at least one direction of 0.5 to 20 μm.
12. A negative electrode, characterized in that the negative electrode comprises a negative electrode active material comprising the silicon-based material according to any one of claims 1 to 11.
13. Electrochemical device comprising a negative electrode, characterized in that the negative electrode comprises a silicon-based material according to any one of claims 1 to 11.
CN202310725979.8A 2023-06-16 2023-06-16 Silicon-based material and electrochemical device comprising same Pending CN116666591A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117080420A (en) * 2023-10-16 2023-11-17 瑞浦兰钧能源股份有限公司 Negative plate and battery

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117080420A (en) * 2023-10-16 2023-11-17 瑞浦兰钧能源股份有限公司 Negative plate and battery

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